In the past, the process of laying sod has been a very labor-intensive and time-consuming process. Sod is generally grown in large quantities in commercially-owned fields or nurseries. The sod is then cut into short, rectangular strips or longer strips which are formed into small rolls for storage and transport. After being transported to the desired location, the sod or small sod roll must be manually placed in a specific position, even with any previously laid sod, to cover the ground and form a lawn.
More recently, sod has been cut in rectangular strips of greater length and formed into very large rolls. In this form, the rolls of sod can be unrolled to cover a greater area more quickly and easily than the smaller, manually placed rectangular pieces or small sod rolls. Additionally, by using longer, wider rolls of sod, the number of seams between pieces of sod is reduced, producing an even, more desirable appearance.
These larger sod rolls often weigh in excess of one thousand pounds, and thus require the use of a sod laying machine or other equipment. A significant problem with such machines stems from the propensity of the rolls of sod to tear or break as it is being laid by the machine. These breakages can be caused by operation of the machine or variations in the condition of the sod itself within the roll. If the sod breaks while the machine is in operation, the operator must stop and readjust the machine to compensate for the gap left in the sod. Additionally, due to variations in terrain or speed of the machine, the sod can buckle, causing an unsightly appearance. Unless the user can adjust the speed of the unwinding sod roll (slower to cause the roll to pull up slack or faster to allow for more distribution over hills or rough terrain), the user will be required to stop the machine and adjust the sod at a significant loss of time.
U.S. Pat. No. 5,129,462 (granted to Mail) and U.S. Pat. No. 5,307,880 (granted to Woerner) both employ the use of a sod carrying apparatus mounted above a pair of driving tracks. When the driving tracks are propelled forward by the user, the roll of sod is rotated and caused to unroll onto the ground in front of the machine. U.S. Pat. No. 5,307,880 (Granted to Woerner) is distinguished in that it can dispense the sod in either a forward or reverse direction. The inherent problem with both of these machines is the fact that the speed of the dispensing roller depends solely upon the speed of the driving tracks, with no apparent method for either increasing or decreasing the speed at which the sod is placed on the ground. If the sod buckles or tears, the operator is still required to cease operation of the machine to adjust for the abnormality in the lain sod.
U.S. Pat. No. 5,215,278 (granted to Hess) shows an apparatus comprised of a conveyor mounted on a frame, which in turn is supported by ground engaging wheels. When the apparatus is pulled, the wheels are rotated and move the apparatus forward, while at the same time, the conveyor feeds sod from the roll onto the ground. While this apparatus successfully lays the sod on the ground, it requires the user to employ another vehicle to propel the apparatus. Because the user is engaged in the operation of the pulling vehicle, he is distanced from the sod being laid on the ground and unable to easily monitor its progress for breaks or buckles. Additionally, even if the operator does notice problems with the sod, as with the previously discussed machines, there is no means to adjust the speed of the conveyor, as it dependent on the speed of the ground engaging wheels.
U.S. Pat. No. 4,878,542 (granted to Brouwer et al.) describes a four-wheeled vehicle having a hydraulically controlled arm extending to the front of the apparatus to hold a roll of sod. The sod is released downward, towards the back of the apparatus and passes underneath the vehicle as it is dispensed. The operator's seat is located in the front of the vehicle, giving the driver a view of the sod as it is dispensed onto the ground. While the driver is able to see any abnormalities or breaks in the sod as it unrolls, it cannot prevent any buckles from occurring once the sod is placed on the ground. Because the sod passes underneath the wheels of the apparatus, the weight of the machine presses the sod into the ground, making buckles in the sod extremely difficult to remove.
From the foregoing discussion, it can be clearly seen that it would be desirable to provide a means for laying large rolls of sod by unrolling such rolls in an even and consistent manner. It is also desirable to provide a means by which the operator may adjust the speed by which the rolls of sod are unrolled, so as to more easily compensate for breaks or buckles in the sod without completely ceasing operation of the machine. It is also desirable to provide a means of installing sod which is easily maneuverable for difficult terrain or in limited spaces and further, can be utilized by a single operator.